Chronic pulmonary inflammation is an important risk factor for lung cancer. Accumulating data have shown that smokers with chronic pulmonary inflammation have a higher risk of developing lung cancer as compared to smokers without pulmonary inflammation. Molecular links between pulmonary inflammation and lung cancer are microRNAs (miRs) and pro-inflammatory signaling pathways such as Akt, NF-?B and STAT3. Therefore, targeting of miRs and pro-inflammatory signaling pathways by chemo preventive agents could suppress lung tumor genesis. The main goal of this project is to assess the efficacy of combinations of indole- 3-carbinol (I3C) and silibinin (SB), two widely consumed naturally occurring phytochemicals, to inhibit chronic inflammation-related lung cancer and determine the mechanisms involved. In preliminary studies, we developed a novel and facile mouse model for inflammation-driven lung cancer and showed in in vitro studies with lung cancer cell lines that the ant proliferative and apoptotic effects of I3C plus SB were paralleled b decreased activation of the pro-inflammatory proteins Akt, NF-?B and STAT3, down-regulation of miR-21 and miR-155, but up-regulation of PTEN and SHIP1, targets for miR-21 and miR-155, respectively. Therefore, we hypothesized that inflammation-driven lung tumor genesis could be inhibited by I3C plus SB, at least in part, via modulation of miR-21 and miR-155 levels in association with inhibition of Akt, NF-kB and STAT3 signaling. This hypothesis will be tested by the following three Aims: Specific Aim 1: Evaluate the efficacy of I3C plus SB against NNK plus LPS-induced mouse lung adenocarcinoma, inflammatory milieu and dysregulation of miRs. Specific Aim 2: Determine the efficacy of anti-miR-21 and anti-miR-155, alone or in combination, to inhibit inflammation-driven lung tumor genesis in A/J mice. Specific Aim 3: Elucidate how I3C plus SB interrupts the inflammatory positive feedback loop involving Akt, NF-kB/STAT3, and miR-21/miR155 and thus inhibits cell proliferation and survival. Impact/Significance: The results of this study could establish the basis for future clinical trials of I3C plus SB for lung cancer chemoprevention and provide a better understanding of the molecular events underlying inflammation-driven lung tumor genesis.